Design of biobased (co)polymers and nanoparticles through emulsion polymerization of biosourced monomers
Résumé
From a global point of view, the development of greener processes and the use of “greener” building blocks are one of the main challenges that synthetic chemists must address to solve current environmental and economic issues. Polymers represent an important class of materials widely used in industrial applications. Nevertheless, synthetic polymers are essentially based on petrosourced monomers. To achieve sustainable chemistry, several teams are currently investigating the synthesis of biosourced polymers.1–3 In our group, we combine the use of the polymerization induced-self-assembly (PISA) technique and reversible-deactivation radical polymerization (RDRP) in green solvents (ultimately in water) to engineer nanoparticles (NPs) based on new biobased amphiphilic copolymers. While the RDRP -such as the reversible addition-fragmentation chain transfer (RAFT) polymerization - allows the preparation of defined polymers in a controlled fashion4, the PISA approach, proceeding in heterogeneous potentially “green” conditions, relying on the use of a hydrophilic macromolecular control agent to promote the emulsion polymerization of hydrophobic monomers, leads to the formation of amphiphilic block copolymers that self-assemble into self-stabilized nanoparticles (NPs), avoiding the use of any free surfactant in the medium.5–7
In this work, hydrophobic and hydrophilic biobased radically polymerizable monomers were either purchased or designed from biosourced precursors. Then, a hydrophilic biobased reactive block, namely a macro-RAFT agent, was used in the PISA approach to generate completely biosourced NPs. The polymerization conditions were varied (molar mass of macroRAFT, DP targeted, pH) in order to achieve the in-situ formation of stable NPs. The molar mass of the amphiphilic diblock copolymer was assessed by size-exclusion chromatography (SEC), while the shape and size of the final NPs were determined by means of dynamic light scattering (DLS), small-angle X-ray scattering experiments (SAXS) and cryogenic transmission electronic microscopy (cryo-TEM) .
References :
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